Five months after agreeing to go on a date with tight end Colton Underwood, Olympic gymnast Aly Raisman has let the cat out of the bag and revealed they are officially a couple!

The two walked the red carpet on Monday night at the Sports Illustrated Sportsperson of the Year Ceremony 2016 at Barclays Center of Brooklyn, New York.

The 22-year-old tells PEOPLE exclusively that the couple “kept it quiet for a while” but they have been dating since the VMAs in August after Underwood, 24, asked Raisman out over social media and she accepted.

“We happened to both be in Denver at the same time,” she says. “I was there for less than 12 hours, he was flying in for just a few days. it just ended up working perfectly.”

The couple looked “really happy together” inside the ceremony, a source tells PEOPLE. “He had his arm around her throughout the dinner and they laughed a lot.”

Raisman tells PEOPLE that Underwood, a free agent, drove 90 minutes back and forth to meet her for their second and third dates. She has met Underwood’s family and will be seeing them again for the holidays.